Lock collar swaging tools



` Sept 25, 1956 P, C, KOENIG 2,764,045

LOCK COLLAR SWAGING TOOLS Filed Jan. 19, 1953 @M f@ 'E /0 Ill/112 49 O United States Patent O LOCK COLLAR SWAGING TOOLS Philip C. Koenig, Seattle, Wash., assignor to Boeing Airplane Company, a corporation of Delaware Application January 19, 1953, Serial No. 331,835

Claims. (Cl. 7846) Lock bolts are used in various types of construction, and especially in aeronautical construction. Such lock bolts, in one widely used form, consist of a headed bolt passed through registering holes in structure to be held together, with its head bearing at one face of the structure and its shank, protruding beyond the opposite face, circumferentially ridged and grooved at intervals, with a lock collar surrounding such shank, the soft metal of which has been swaged and thereby crowded radially inwardly within the grooves and axially towards the structures face opposite the bolts head, to press together the opposite faces of the structure and to resist pulling off.

Such lock collars are commonly swaged in place (see Torreson Patent No. 2,542,376 and Keller Patent No. 2,395,667) by recessed one-piece dies which have an appreciable draft angle, so that the metal is crowded axially to an appreciable extent-as is desirable to press the lock collar against the structures face--as well as radially inwardly; this rather large draft angle is also required in order that the die may be lifted off the swaged collar. Such collars are normally of material, such as 24ST dural in aeronautical work, which work-hardens. This is desirable in that it increases the resistance of the lock collar to pulling off the lock bolt but since the lock collar as a whole is continuously being impacted and urged ahead of the die, its metal becomes increasingly tougher as the swaging operation proceeds, and it is not easy to complete the swaging fully, nor is there any certain gauge to tell the workman when the job is properly completed. These dilculties are pronounced in large collars especially, although by no means confined thereto. As a result, even with conscientious workmen there is a too high percentage of rejections, and inspection must be meticulous, thorough, and correspondingly expensive, to discover defective lock bolts, and the operation as a whole becomes unduly, and yet apparently necessarily, expensive. The inspector must use special stepped diameter go-no-go gauges which in eiect determine the distance between the workpiece and a certain predetermined diameter on the conically swaged collar. This takes time and is sometimes inaccurate, particularly when the lock bolts are located adjacent the web of an I-beam or similar structure.

lt has also been proposed to use a one-piece die which crowds the lock collar metal primarily radially inwardly, and which may have a reduced throat which passes axially along the exterior of the collar as it swages the latter. This helps eliminate the progressive or cumulative Workhardening, but it introduces a further complication. In such cases it has been found impossible to pull the die axially olf the swaged lock collar, for the metal as it passes above the throat reacts expansively, and the throat itself fits tightly. In such cases-see Huck Patent No. 2,531,049-it has been found necessary to incorporate a stripper within the die, which is repeatedly impacted and forced against the end of the swaged collar to drive the latter out of the dies recess. Not only does this produce mechanical complications in the die, but it tends to upset the swaged end of the collar, increasing the diihculty of 1 projecting portion of the lock bolt. It is desired to call 2,764,045 Patented Sept. 25, 19,56

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its withdrawal, and in itself it may weaken or loosen the bolts securement, and may destroy in a measure the datum-the external diameter of the collarfor the inspection procedure.

It is the object of this invention to avoid the cumulative work-hardening and build-up of resistance to swaging of the lock collar, yet at the same time to avoid the necessity for driving the swaged lock collar out of the die. In effect, according to the present invention the advantages of the last-mentioned prior method and tool are achieved, but its disadvantages are avoided, and removal of the die from the swaged collar is accomplished as readily as by the use of the wide draft angle dies first mentioned, yet without the disadvantageous cumulative increase of workhardening and the consequent uncertainty that the swaging operation is properly completed, such as characterize that first-mentioned tool and method.

More particularly, according to the present invention, provision is made for the swaging action to require substantially constant force until virtually completed, and to proceed progressively, in constantly shifting zones, along the length of the lock collar. Thus the workman will encounter a minimum of resistance at any given time, and generally constant resistance at all times, and will not encounter progressively increasing or cumulative resistance. Moreover, the swaging creates no excessive nor progressive work-hardening, but can proceed to a point where it is easy to determine by an abrupt increase of resistance, or by visual inspection, or both, and without the necessity of using any inspection gauges, that the swaging has been completed to the required point, and thus time and effort are saved in doing the job and in inspection. Such method and such swaging die will be especially valuable in swaging work-hardening metals, but will also be useful regardless of that characteristics: of the collar metal.

In the accompanying drawings are shown several progressive steps in the method, utilizing the improved swaging tool of this invention.

Figure l is an axial section along the lock bolt and collar and through the sheets to be held thereby, and through the swaging die and its die holder, showing parts in position for the iirst step of the process, namely, the application of the die to the lock collar.

Figure 2 is a view similar to Figure l, but showing the swaging operation in progress, and partially completed.

Figure 3 is a view similar to Figures 1 and 2 showing the swaging operation completed; certain dimensions are exaggerated for clarity.

Figure 4 is a similar view showing the final stage of the operation; the disengagement of the die from the fully swaged collar.

It will be understood that A and B are intended to represent two sheets which are to be secured together by4 threads) at its opposite end, indicated at 11, and defining between them valleys or circumferential grooves at 12. The shank of `the lock bolt is long enough that with its head 19 fitted against the plate B t-he solid portion of its shank substantially tllls the registering holes drilled in the plates A and B, and the ridged and grooved portion of its shank extends an appreciable distance above the plate A, opposite the plate B which is engaged by the head 19.

The locking collar 2 is of standard form also, and consists normally of a generally cylindrical sleeve portion and a flange 20 which is intended to seat against the plate A when the lock collar 2 is slipped or forced onto the attention to the fact that the flange is arranged at an abrupt angle to the sleeve portion of the lock collar 2, as this is important in the determination of when the swagirig operation is completed, as` will appear later.

' Contrary toY prior practice, .the swaging die, according to the present invention, is not a solid die but is a split die-that is to say, it is formed of several (two, threeor more, according to the size of the collar to be swaged) parts which are separable one from another along generally axial planes. The two parts 31 and 32, separable along the plane indicated at in Figure l, arc shown in the drawings. There may be means for yieldingly holding the die parts in contiguity, and such means are illustrated herein in the form of a garter spring 33 surrounding the die near its outer or collar-engaging end,

andin addition the die is formed with a reduced and elongated shank 34 at the end distant from its entrance, formed with. a flange 35, and encircled by a spring clip 36, or the like, whereby this end of the die may also be held with its parts in contiguity, but yieldingly. The spring means at 33, or the spring means at 36, either one may constitute the sole means to hold the die parts thus yieldingly in continguity, or by proper arrangement neither such means may be required.

The die, the interior construction of which will shortly bc explained in detail, is received within a recess 40 in the end of a die holder 4 in such a way that force applied to the die holder 4 will be transmitted to the die and translated into a swaging force acting axially upon the collar 2 to crowd the metal of the latter inwardly. The die as a whole is somewhat loosely received within the recess 40, except when parts are in position for such forcing movement of the die. By reasons of this loose engagement, the die may slide lengthwise within the recess 40 of the die holder but should be held sutiiciently securely within the recess that while it may withdraw partially from the recess, it may not wholly withdraw therefrom. To this end a set bolt 41, or several such set bolts, may be received in the die holder, and project inwardly close to the reduced shank 34, sufficiently that it or they will engage the head 35 and limit withdrawal of the die to the distance between the location of the set bolts 41 and the head 35, as may be seen by comparison, for instance, of Figures 3 and 4.

Near its open entrance the die is formed with a circumferential ledge 37 located to be engaged by the end 47 of the die holder 4 as a bearing surface for axial forcing movement of the die as a result of impacts axially upon the die. holder. In addition, the entrance to the recess is provided with an inwardly directed circumferential surface 43 which closely embraces a complementaly exterior surface 48 of the die, and when the two parts are thus interengaged the die is inV position for forcing along the collar and the split parts of the die are held securely against relative axial separation. However, the axial length of the circumferentially interengaging surfaces at 43 and 48 is relatively slight, and these surfaces will become disengaged appreciably before the withdrawal of the die ceases by virtue of engagement of a set bolt 41 with its head 35. This is readily seen in Figure 4. Above the circumferentially engaged, portion at 48 the exterior of the die, as is indicated at 49, is somewhat less in diameter than any portion of the recess 40 with which it might come into contact, the die-holder being enlarged as indicated at 42.

Interiorly, the die is formed with a tlared entrance at 38, graduated from a size suiiiciently large to iit upon the upper end of the lock collar 21, to a size to crowd inwardly and downwardly toward the head 19 the metal of the collar. This flared surface 38 terminates in a reduced throat 39 which is of approximately the size to which it is desired the exterior of the lock collar be swaged. This throat 39 is of slight axial extent, and the swinging sur.- facesy 38, 39- are together of an axial extent whichy is but a fraction of the length of the lock collar 2. Above the reduced throat 39, the walls of the recess within the die are relieved so that there can be no contact above the throat between the die and the already swaged exteriorof the collar.

The swaging force may be applied to the die holder 4 by blows upon its upper shank 49, which may be received within the chuck of a hydraulic or air hammer, or the like, as is customary in such swaging dies, or the force may be applied inv any convenient way, continuously or repeatedly. During thev swaging operation the bolts head i9 may be backed by abucking tool 5, which resists driving out of the bolt from the work.

The iirst step-in the process is to apply the die, held within its die holder,` to the end of a collar 2 in the manner indicated in Figure l. Even before there has been any swaging force applied, the contact between the end of the collar and the entrance to the die will urge the die into its recess 40 in the die holder. VThe interengag'ement of the circumferential surfaces at 43 and 48 will hold the die parts closed againstA radial separation, and will bring the endwise bearing surfaces at 37 and 47 sus'otantially into contact. Also the die will be rather accurately centered uponv the collar.

Now by applying a swaging force downwardly as illustrated in Figure 2, to the die holder, the swaging operation commences. The flared swag-ing lsurfaces at 38 crowd the metal of the collar in a limited zone radially inwardly and axially downwardly, and the inward forcing is completed and assured by the reduced throat at 39. By virtue of `the fact that the swaging surfaces do not attempt to crowd all the metal of the lock collar inwardly and downwardly ahead. of the die, the swaging operation proceeds only 'in approximately the narrow zone of greatest pressure in the vicinity of the surfaces 38 and 39. The metal in advance of these surfaces is not appreciably crowded and consequently does not become work-hardened but remains sufficiently soft that the force required to swage it `inwardly 4in return is not appreciably greater than that which was required to swagc the first part of the collar. As a result,.the swaging proceeds rather uniformly and with uniform force throughout the length of the collar, until parts reach the positions illustrated` in Figure 3. When they reach this position, it will be noted that the outer end of the die comes to bear upon the iiange 20 of the lock collar, and the flared swaging surface 38 has erased the abrupt angle between this ange and the sleeve portion of the collar. When parts reach this position, and only when they do, not before, there comes an abrupt increase in the resistance to swaging and this abrupt increase of resistance has beenl found to constitute a very reliable guide to indicate when the collar has been completely and properly swaged in place. This furnishes a workable guide for the workman, and the inspector needs only to see `that -the abnupt right angle between the tiange 20 and `the `sleeve portion of the lock collar has been erased to know that the lock collar has been properly swaged in place. Gauges may `be applied as has been the prior practice, but they will be needed primarily for spot checks, and inspection will be reduced to a simple visual inspection for' the most part.

During the swaging operation, the metal of the collar is compressed radially inwardly and to some extent axially, and as the narrow throat 39 passes downwardly along the collar 2, the metal of the collar will react expansively outwardly. It has been attempted to illustrate this particularly in Figure. 3. ltis in particular to avoid any contact of the die with the already swaged metal `of the Collar above the narrow throat, and resultant cumulative resistance, ythat the dies recess has been relieved above the throat. This limits the extent of work-hardening of the metal', and materially reduces the force required, and inl eiiect. eliminates any accumulation of resistance to thc swaging,` keeping the swaging force uniform until such beenrexplaledi, l

However, the swelling ofthe swaged :collar would make extremely diicult the disengagement of the die from the collar after completion of the swaging, and would require a stripper device, if it were not for the fact that the die is a split die. The die being split, contrary to normal practice, it becomes possible to eifcct the final operation of the method, as illustrated in Figure 4, by withdrawing the die and die holder upwardly and away from the work, and at the same time to incline them laterally, which actions in combination have the effect of withdrawing the die from its die holder, at least to the limit permitted, which withdrawal disengages the circumferential bearing surfaces at 43 and 48 from contact one with another, and permits the split parts of the die to separate along axial planes in opposition to the spring means as at 33 and at 36, which normally hold them in contiguous relationship. This splitting of the die makes easy its withdrawal past the swelled outer end portion of the swaged collar, and only minimum force is required. Furthermore, there is no tendency to deform lthe collar in an undesirable manner, nor any need to drive the die off the swaged collar, as has been the practice heretofore when solid dies with narrow constricted throats were employed.

I claim as my invention:

l. A tool for use in swaging a deformable metal coliar upon a lock bolt, comprising in combination with a recessed die holder, a split die received in such recess and formed of complemental parts separable along general-ly axially disposed planes, said die being formed interiorly with a circumferentially disposed swaging throat of minimum diameter, located somewhat inwardly of the dies entrance, the dies interior being radially enlarged in the portion between said throat and the entrance, and being also radially enlarged in the portion located axially inwardly from said throat; said die and the die holder being formed with complementally engageable, generally transverse bearing surfaces for forcing the die in the axial direction by force applied to the die holder, and being further formed with complementary engageable, generally circumferentially disposed surfaces located in the vicinity of the throat, for interengagement when said transverse bearing surfaces are operatively interengaged, to retain the parts of the die operatively grouped, and against separation; the respective icircum-ferentially disposed surfaces being of a given axial extent, and the die and die holder being each relieved axially inwardly of said circumferentially disposed surfaces to space them apart when the respective circumferentially disposed surfaces are disengaged by relative axial movement, and means to terminate axial withdrawing movement of the die from the die holder after withdrawal to a distance sufficient to: disengage the respective circumferentially disposed surfaces and so to enable transverse separation of the `so-withdravvn die parts.

2. A tool for use in radially compressing a soft metal lock bolt collar surrounding such a bolt by an axially directed swaging operation, comprising a die split along generally axial radial planes to define a plurality of complemental parts, said die as a whole having a first external circumferential surface located adjacent its entrance, and a second external circumferential surface which is of smaller radius, located more distantly from its entrance, and having also an external bearing surface disposed generally normal to its axis, and said die having an internal end-facing outwardly flared swaging entrance terminating at its inner end in a reduced throat, leading in turn to a recess of a size radially larger than such throat; a die holder recessed to receive said die, having an entrance defining an internal circumferential surface of a size to surround closely the dies aforesaid iirst external circumferential surface, and a bearing surface complemental to the dies bearing surface, the two bearing surfaces being located, in the axial direction and relative to the complemental circumferential surfaces of the die and die holder, to interengage for transmission of an axially directed force when lthe two latter surfaces are interengalged to prevent separation of the dies complemental parts in the radial sense, said two complemental circumferential surfaces being relatively of a length to disengage upon limited withdrawing movement of the die axially outwardly of the die holders entrance, and by such disengagement and the consequent disposition of the die holders circumferential surface adjacent the dies reduced second external circumferential surface, to permit radial separation of the dies parts, and means to lim-it axial withdrawing movement of the die relative to the die holder to a distance somewhat in excess of that required to disengage their complemental cincumferential surfaces.

3. A swaging tool as in claim 2, including an axially directed shank formed integrally with and mounted externally of the die, and terminating at its end distant from the dies entrance in a radially outwardly directed flange, and a lset bolt carried by the die holder and projecting generally radially inwardly towards said shank in position to intercept and engage said flange upon withdrawing movement of the die from the idie holder, the whole constituting the means to limit axial withdrawal, and the shank being of such length relative to the set 'bolt and to the length of the respective complemental circumferential surfaces as to permit withdrawal of the die from the operative position wherein the respective bearing surfaces and the respective circumferential surfaces are in engagement, to a releasing position wherein such respective surfaces are disengaged, and the die holders cincurnferential surface is adjacent the dies reduced second extern al circumferential surface.

4. A tool for use in swaging a deformable metal collar upon a lock bolt, comprising in combination a recessed die holder, a split die received in such recess and formed of complemental parts separable along generally axially disposed planes, and means interengageable between the die holder and the die for limited axial withdrawing movement, and return, of the die relative to the die holder, said die being formed interiorly with a oircumferentially disposed swaging throat of least diameter, located somewhat inwardly of the dies entrance, the dies interior being increasingly radially enlarged in the portion between said throat and the entrance, and being also radially enlarged in the portion located axially inwardly from the throat, complemental means formed on said die and the die holder for interen-gagement to force the die in the axial direction by force applied to the die holder, and to limit entrance of the die into the die holder, and at the same time to retain the parts of the die operatively grouped, and against separation, said means being of an axial extent to become disengaged by withdrawing movement of the die from the die holder within the limit of their relative movement, and the die and die holder being of relative sizes in the portions which are juxtaposed when so withdrawn, to permit transverse separation of the sol-withdrawn die parts.

5. The swaging tool defined in claim 4, wherein the enlarged portion of the die between the throat and its entrance is conically ared from the throat outwardly to the entrance.

References Cited in the file of this patent UNITED STATES PATENTS 1,464,434 Ljungstrom Aug. 7, 1923 1,952,245 Garner Mar. 27, 1934 2,327,936 Slater Aug. 24, 1943 2,369,260 Slater Feb. 13, 1945 2,397,076 Keller et al Mar. 19, 1946 2,542,376 Torresen Feb. 20, 1951 2,630,623 Chrisholm et al. Mar. 10, 1953 2,630,916 Blair Mar. 10, 1953 

